1. Field of Invention
The invention is directed to disconnect devices for downhole strings and, in particular, disconnect devices that permit disconnection of one part of a string from another part of a string in oil and gas exploration and production operations.
2. Description of Art
In the drilling, completion, and workover of oil and gas wells, it is common to perform multiple operations downhole in the wellbore. It is also common for one portion of a tool string having multiple tools to be run-in to the wellbore where a downhole operation is performed that results in a part of the tool string being left within the wellbore so the tool string can be retrieve or moved to another location within the wellbore where additional operations can be performed. To permit such movement of the tool string, the part of the tool string to remain in a certain location must be disconnected from the rest of the tool string.
Alternatively, one part of a string could become stuck within a well necessitating the disconnection and retrieval of the other part of the string. Disconnection from the stuck portion of the string is facilitated using a disconnect device.
Further, during run-in of a casing string a problem could arise where the shear rams of a blowout preventer could not shear the casing string. Disconnection from the casing string above the blowout preventer would allow the casing string to fall through the blowout preventer allowing the shear rams to close-off the well.